Answer to question how to display zero instead of NaN in XSLT for non existing node containing number values (kind of ifnull or coallesce functions that are available in SQL).

You can do it by standard expressive XSLT way, with using variable and <xsl:choose>, or abuse built-in sum() function and do whole thing in one line.

Standard way:

<!– read the value –>
<xsl:variable name=”val”>
<xsl:choose>
<xsl:when test=”//number[1]”><xsl:value-of select=”//number[1]”/></xsl:when>
<xsl:otherwise>0</xsl:otherwise>
</xsl:choose>
</xsl:variable>
<!– print the value out –>
<xsl:value-of select=”$val“/>

 

Quick way:

<!– read and printout –>
<xsl:value-of select=”sum(//number[1])“/>

 

Both codes will print value of first node named number or zero if the node is not present.  Because it is a sum() function, it’s a good idea to limit nodeset only to first one, otherwise you will get a sum of all existing number nodes.

Btw. do you know the best XSLT reference out there ? No ? Look at ZVON XSLT reference.